Selective Noise Reduction?

Questions and answers about processing in StarTools and how to accomplish certain tasks.
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juno16
Posts: 18
Joined: Thu Dec 06, 2018 3:18 pm

Selective Noise Reduction?

Post by juno16 »

Hi Ivo,

Just a quick question. Is there a way to apply noise reduction to only a part of an image? I have an image where I really like the star background. After noise reduction, the background has kind of a "mottled" appearance. I tried some of the settings and could not quite get the right "look" that I liked.

Can a mask be applied to noise reduction?

Before noise reduction (zoomed to 200%).
NGC 6960 no noise reduction.JPG
NGC 6960 no noise reduction.JPG (137.29 KiB) Viewed 175 times
Post noise reduction.
NGC 6960 noise reduction in Startools.JPG
NGC 6960 noise reduction in Startools.JPG (92.67 KiB) Viewed 175 times
I prefer a bit of noise over the "mottled" appearance.

Thanks,
Jim
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admin
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Re: Selective Noise Reduction?

Post by admin »

Have you tried Denoise 2 (Grain Equalization rather than Grain Removal when switching Tracking off) in 1.6, or the updated Denoise in the latest 1.7 alpha? 1.7 has a Uniform Grain Retention parameter that sounds like it may be what you're after.
Ivo Jager
StarTools creator and astronomy enthusiast
juno16
Posts: 18
Joined: Thu Dec 06, 2018 3:18 pm

Re: Selective Noise Reduction?

Post by juno16 »

admin wrote: Sat Sep 12, 2020 3:02 am Have you tried Denoise 2 (Grain Equalization rather than Grain Removal when switching Tracking off) in 1.6, or the updated Denoise in the latest 1.7 alpha? 1.7 has a Uniform Grain Retention parameter that sounds like it may be what you're after.
Thank you Ivo!

I did try Grain Equalization Denoise in 1.7 alpha. I went ahead and tried grain removal just to see the difference and it didn't help.

I was just curious if there was a way to just mask the target and apply Denoise there. I am fine with the background stars.

No problem. The dataset is somewhat poor (only two hours integration) and in Bortle 8 skies with a dslr.

Grain equalization denoise worked great on the nebula (Western Veil), but the dim background stars were kind of smudged.

Thanks for responding and I very much enjoy Startools!
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